Crickly, Crackly Fermented Potatoes

Your potatoes will shrink significantly during fermentation. Way more than your other pickled veg does.. You may want to add more potatoes in after a couple days just to get full benefit from your jar (or not). Roughly 2.5 pounds post-fermentation will fit on a sheet pan, so you may need to use two smaller pans if you do add more spuds.

The story goes like this: A few years ago, I was in a program for cooks/chefs and food writers at Audrey Claire’s COOK. One of the chefs who was teaching us was a classically trained French chef (he’s American, but was trained in France and cooks French food at his restaurants). He made this bold claim: No restaurant is making French fries in house, or if they are, their fries are probably not good fries. They’re not doing it, he said, because for French fries to be halfway decent, they have to soak for at least 36 hours, and very few restaurants have room in their walk-ins for the giant vats of soaking sliced potatoes they’d need to fill fry demand. He said he didn’t know why it was such an important step, just that soaking was the only way to do it and achieve worthy results.

Pre-soaking potatoes will give you the crisp you want!

I’m generally not down with the word “only” but I was intrigued by his strong feelings on the matter and excited that the process he described was, basically a short ferment. I went home and immediately started playing around with this. The deep-fried Sweet Potato Fry Nests in Ferment Your Vegetablesare a result of this revelation. Those party-worthy sweeties are a little sexier, a little more work, and a lot more indulgent than these which are super simple and can easily be added to a weeknight meal.

The best part about these potatoes is the texture. You know the texture of a really great, thick potato chip? Like when they have visible bubbles under the skin and the exact right bite? Think of that transformed into roasted potatoes, with crisp exteriors and smooth, puffy insides. Plus, these potatoes have the added, fermenty advantage of tang and, presumably, somewhat lowered sugar content.

Pre-roast “tater tarts”

This is my 2nd favorite way to eat potatoes (because mashed potatoes will win any potato contest ever and your arguments are invalid) and I’m excited to share the simple process with you.

Note: In case you missed it, these will not be probiotic after cooking. That loss is a low price to pay for this flavor and texture, IMO.

I like mine very browned (these were cooked for 50 minutes). You don’t have to get them this dark to have the crisp bite!

One other thing on the texture: these are not super creamy. The goodness of this is all about the crusty outer shell, and if they ferment for longer than 5 or 6 days, they can actually get a little hollow on the inside during roasting. I DO NOT MIND THIS AT ALL. I think it’s actually wonderful, but if you’re looking for those dinner home fries that are mostly cream with a teensy bit of crunch, look away. This isn’t the recipe for you.

One other thing on flavor: Fermented for a week or more, they become what my husband calls “tater tarts” because the acidic flavors are quite pronounced at that point. This is my preferred way to eat them, but if you stop fermentation earlier than that, you’ll still get some of those delightfully balancing acids.

3 four-inch (100 mm) sprigs rosemary, and more for garnish at roasting time (optional but delicious)

4 peeled cloves garlic, divided (optional)

2 tablespoons (30 ml) olive oil

Serve as a side, hot from the oven.

The How-To

Quarter or halve potatoes into pieces that are roughly 1.5 inches square. Remove any eyes or greens spots, but again, otherwise keep them unpeeled.

Mix salt into water until dissolved. Add 2 cloves of garlic into the jar and top with some potatoes. Layer in rosemary sprigs, but end with potatoes on top. Jar should be full to about 1.5 inches below the rim, or to the bottom of the threads.

Add brine to the jar to just cover potatoes and add your weight. Once the weight is applied, the brine layer should still be 1 inch below the jar rim and no more than half an inch over the potatoes.

Close or cover jar, according to which type of weight you’ve chosen and ferment at room temp, out of direct sunlight for 4 to 10 days. 4 days will be slightly less crisp, but they’ll have more body. 1o days will be quite sour and have a lot of puff.

Strain off pickling liquid (feel free to use this for a large pot of soup or anywhere else you’d like salty, sour liquid, but remember it’s VERY salty compared even to normal pickle brine) and pat potatoes dry. Compost the rosemary sprigs and garlic.

Heat the oven to 400 F and spread the potatoes in a single layer on a large, lined baking sheet. Add peeled garlic cloves and add finely chopped rosemary from another 3-4 inch sprig of rosemary, if using. Drizzle with olive oil and toss to coat. Place it in the oven for 40-50 minutes. They’re ready when they’re deeply browned and have pronounced bubbles under the skin.

Serve as close to immediately as possible. They will stay kinda crisp in the fridge for a couple days, but they won’t be company ready again.

*Salt quantity in this recipe has been updated to reflect readers’ feedback. I tested it with lower salt and it still crisps up nicely.*

The link to my book (above is an Amazon Affiliate link). That means that if you buy stuff after you click it, I get a small percentage back from any purchases you make. It doesn’t add anything to your purchase and it’s the only way I make money off of blog posts, so I really appreciate when you do that!

According to some of the Dr.s that appear on D.r Oz Show, & on those “PBS Pledge Month” shows: Anything fermented, will make carbohydrates either fully or partially resistant. Also they lower the glucose levels in the body & bring a lot of healthy nutrients to the cells of the body. Just passing on some FYI. Bon Appetite.

Thank you for this recipe! I love potatoes, especially roasted. I put on a batch today and can hardly wait to try them. Since I’m in Canada and use metric, I appreciate that you add metric conversions, however I noticed that 2.75 cups was equivalent to 623 ml instead of 412 ml (I went ahead and used 623ml). I also have your book and love it. Thank you again!

I made these earlier today and they were fantastic! I used bay leaves and garlic powder instead of the rosemary and fresh garlic, and only did a two day ferment as my kitchen stays pretty warm. I think this is going to be how I make home fries from now on. I’ll probably even add this extra step to other potato recipes (especially mashed potatoes) as the flavor payoff is worth it.

I made these tonight after a 7 day ferment and though the texture was amazing, they were so salty they were inedible – such a bummer. I followed the recipe precisely, or so I thought…going to try again this week.

Thanks for reporting back. I do definitely like them salt, but I’m honestly getting insanely mixed feedback (from way too salty to not salty enough), so I’m going to update the recipe with a range. It’s great that so many people are making this! Do try again with a lower amount of salt. You can always add salt after, but I definitely want to use enough to slow the ferment and create a crisp potato.

Since you are not using a culture starter, when you say “cover or close the jar” do you still mean to have it open and covered by something like cheesecloth, but not a tight jar lid in order to wild ferment?

Hi Sarah, Vegetable fermentation does not require a starter culture (and generally speaking, a starter culture will give you worse results than not using one, IMO & IME). Lactic acid bacteria are on the veggies because they’re in the soil, and their the probiotics you’re trying to cultivate. They prefer airless environments, so no, you definitely don’t want to cover your jar with cheesecloth.

I haven’t every used the Mortier jar, but google tells me it has a water seal. Using the jar according to the instructions that came with it should give you the appropriate airless conditions.

Cooking above 90 degrees will likely kill the probiotics, so no, there won’t be any that retain the probiotics. There are lots and lots of ways to get those good bugs into your diet (many on this site). This recipe is employing fermentation for maximum flavor and crisp.

This is something you can definitely research! Different bacteria survive at different temps (cold and hot) even specific species in the lactobacillus genus. Soil bacteria have been found in countless studies to function best at “room” temp and be outpaced by competitors (or die) at sustained periods of time at substantially warmer or substantially cooler temps.
I definitely recommend doing a bit of googling if this interests you!

My point in this post is that if you’re fermenting for probiotic bacteria, this isn’t the best recipe. If you’re fermenting for flavor and texture, it’s a great option. I hope that clarifies.

I’ve been a fermentation fiend now that Ive discovered it and am excited to try these with my next winter CSA pickup. Thanks! And for your site in general — your encouraging my new kefir “pet” parenting too!

This was a HUGE FAIL! After 5 days, my jar was leaking and my potatoes were reeking. The lid was bulging. I opened the jar in the sink, and the liquid foamed up and over the sides of the jar, ending with a thick white foam that stood up about two inches from the top of the jar. There was a black substance on the inside of the jar lid and the liquid that leaked out of the jar into my cabinet was dark. The rotten potato smell was horrible. Some of the potatoes near the top of the jar had soft spots on them. Most of the potatoes looked fine, were still firm, and didn’t seem to stink, though it was hard to tell because my whole kitchen reeked at that point. I was afraid to use any of them, so I threw the whole batch out.

I THINK I followed your directions to the letter, but obviously something went wrong. Do you have any idea whay could have happened? I’d like to try this again, but I’m not sure I could handle another colossal failure. Other than making milk kefir, which I’m still fairly new at, this was my first attempt at fermentation. Not a good way to start the journey. 🙁 Any advice would be greatly appreciated.

So sorry to hear you had trouble! If this is your first time fermenting, one issue could be expectations. Vegetable fermentation has an aroma that I find pleasant and some people hate (think: sauerkraut). The lid should be bulging if you tightened it completely, but hopefully you checked out the link under “equipment” in the recipe where I discuss weighting ferments in detail (I’ve added it to the body of the recipe as well now) so you knew about different ways to weight and close the jar.

If your potatoes weren’t properly weighted and some were above the surface of the brine, they would get soft. They do need to be submerged, so make sure to check out that part of the recipe and the attached link. The other thing that can impact most of the things you mentioned here is salt, although that would be most likely to be an issue if you didn’t use enough salt, and this recipe calls for more salt than the vast majority of my veg ferment recipes, so I don’t think it’s likely to have been the issue in this case.

Thank you so much for your reply. Now I’m embarrassed: Somehow I missed the part about the lid. I used a glass weight that fit inside the jar and kept the potatoes under the brine, but I screwed the lid on tightly. I really wasn’t expecting the smell. All of the potatoes were submerged, but maybe the soft spots were caused by the gasses that couldn’t escape? Anyway, thanks for your encouragement, suggestions, and the links. I still want to try this recipe, but will start with something simpler.

I have now made these twice using Yukon Gold potatoes. The first time I fermented for four days; the potatoes were fine but had no special taste. Fermented a batch for seven days and WOW LIKE A COW! Rich sour taste when roasted with olive oil, THANKS for your fermen’taters!!

I wouldn’t for a couple reasons: 1) I wouldn’t eat the potatoes without cooking them, even after fermentation, because I don’t know if some of the anti nutrients that are contained in raw potatoes will be altered by fermentation or not (that data doesn’t exist as far as I know). They could be, but I don’t have any way of knowing that.
2) There’s no value in using a starter of any kind in vegetable fermentation. If you read the link ed post, you’ll find a link or two citing studies that show an inferior outcome from vegetables fermented with a starter. Mother Nature (and her soil microbes) do it best.